code: def undefine_alias(self, name):
      if self.is_alias(name):
          del self.linemagics[name]
      else:
          raise ValueError("%s is not an alias" % name)
  
imports: import os
  import re
  import sys
  from traitlets.config.configurable import Configurable
  from .error import UsageError
  from traitlets import List, Instance
  from logging import error
label_desc: Use image node_id 8 for calling the AliasManager obj's underlying member method code with example usage: obj.undefine_alias(name) without return types